Commands by dcabanis (20)

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Open Remote Desktop (RDP) from command line having a custom screen size
This example uses xfreerdp, which builds upon the development of rdesktop. This example usage will also send you the remote machine's sound.

Create arbitrary big file full of zeroes but done in a second
If you want to create fast a very big file for testing purposes and you do not care about its content, then you can use this command to create a file of arbitrary size within less than a second. Content of file will be all zero bytes. The trick is that the content is just not written to the disk, instead the space for it is somehow reserved on operating system level and file system level. It would be filled when first accessed/written (not sure about the mechanism that lies below, but it makes the file creation super fast). Instead of '1G' as in the example, you could use other modifiers like 200K for kilobytes (1024 bytes), 500M for megabytes (1024 * 1024 bytes), 20G for Gigabytes (1024*1024*1024 bytes), 30T for Terabytes (1024^4 bytes). Also P for Penta, etc... Command tested under Linux.

Set laptop display brightness
Run as root. Path may vary depending on laptop model and video card (this was tested on an Acer laptop with ATI HD3200 video). $ cat /proc/acpi/video/VGA/LCD/brightness to discover the possible values for your display.

Get MAC address

A DESTRUCTIVE command to render a drive unbootable
Overwrites the boot sector. Since this doesn't overwrite any data, you can usually recover by re-creating the partition table exactly the same as before you zeroed it. This can also help sometimes if you install a new drive in a Windows machine which can't read it.

list block devices
Shows all block devices in a tree with descruptions of what they are.

Optimal way of deleting huge numbers of files
This command works by rsyncing the target directory (containing the files you want to delete) with an empty directory. The '--delete' switch instructs rsync to remove files that are not present in the source directory. Since there are no files there, all the files will be deleted. I'm not clear on why it's faster than 'find -delete', but it is. Benchmarks here: https://web.archive.org/web/20130929001850/http://linuxnote.net/jianingy/en/linux/a-fast-way-to-remove-huge-number-of-files.html

keep an eye on system load changes
helps you keep watch on the load of a system, without having to stare constantly at the terminal. The -d argument to watch highlights the difference from the last run, making it easier to note how the load is fluctuating. The sed command just strips off the information about how long the box has been up, and how many users are logged in.

List your largest installed packages (on Debian/Ubuntu)
The other commands were good, but they included packages that were installed and then removed. This command only shows packages that are currently installed, sorts smallest to largest, and formats the sizes to be human readable.

pipe commands from a textfile to a telnet-server with netcat
sends commands specified in $commandfile to the telnet-server specified by $telnetserver. to have newlines in $commandfile interpreted as ENTER, save the file in CR+LF (aka "Windows-Textfile") format. if you want to save the output in a separate file, use: $nc $telnetserver 23 < $commandfile > $resultfile


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